1. Field of the Invention
This invention relates to an acoustic radiator that includes an audio speaker and passive radiator mounted in the same enclosure, particularly they are mounted coaxially with the audio speaker surrounded by a passive radiator flexibly mounted in an enclosure.
2. Description of the Related Art
The mounting of an audio speaker and a passive radiator in the same enclosure with substantially trapped air within the enclosure is not a new concept. Two examples of the prior art is illustrated and discussed in a patent by Michael Klasco in U.S. Pat. No. 4,207,963 issued Jun. 17, 1980 and in a patent by Guido O. M. D'Hoogh in U.S. Pat. No. 5,892,184 issued Apr. 6, 1999.
In D'Hoogh's FIG. 3 and the accompanying description he states it is a bass-reflex system which accommodates a passive radiator electrodynamic loudspeaker in a rigid enclosure that has a first opening through which the passive radiator extends and a second opening in which the outer edge of the frame of his loudspeaker is mounted with the majority of the frame of the loudspeaker extending into the enclosure with the motor and cone mounted in a typical fashion in the interior of the frame substantially within the enclosure.
In D'Hoogh the loudspeaker frame is rigidly mounted to the enclosure thus when the loudspeaker is activated the frame and the enclosed mass of the motor magnet does not move relative to the enclosure therefore it does not influence the tuning frequency of the passive radiator.
FIGS. 1A and 1B illustrate, in a simplified format, the prior art audio speaker/passive radiator of D'Hoogh.
In FIG. 1A, a vertical cross-sectional slice has been taken through enclosure 1 having in the top of enclosure 1 a first opening 3 and a second opening 5. Mounted within first opening 3 is a typical audio speaker 7 having a frame 9 with a top outward extending lip 11 mounted rigidly to the top exterior surface of enclosure 1 surrounding opening 3 with the diameter of opening 3 and the diameter of frame 9 below lip 11 being substantially equal with the bulk of frame 9 extending into the interior of enclosure 1. Also shown is a representative vent 10 of a plurality of vents spaced around frame 9 below cone 15. In the bottom of frame 9 there is a typical electromagnetic speaker motor 13 with top and bottom plates with a permanent magnet sandwiched therebetween with the bottom of a speaker cone 15 attached to a voice coil bobbin in communication with the magnet of motor 13 having a dust cap 13′ closing the center of motor 13 plus a spider 14 attached between the bottom of cone 15 and the interior of frame 9. The top edge of cone 15 is attached to lip 11 with a first surround 19. In second opening 5 there is mounted a solid passive radiator panel 21 by means of a second surround 23 between the top edge of passive radiator panel 21 and the top exterior surface of enclosure 1 around the edge of second opening 5. Via vents 10, the air in the space beneath cone 15 and dust cap 13′ and within motor 13 is free to flow throughout the interior of enclosure 1. The interior of enclosure 1 in this configuration is substantially air tight thus when speaker 7 is activated the air pressure within enclosure 1 varies with the movement of speaker cone 15 thus causing passive radiator panel 21 to move inward when cone 15 moves outward and outward when cone 15 moves inward in response to the variation of the interior air pressure of enclosure 1 resulting from movement of cone 15 given a selected time delay.
Since frame 9 of speaker 7 is mounted rigidly to the surface of enclosure 1, there is no movement of frame 9 and the magnet of motor 13 therewithin thus the only influence that causes movement of passive radiator panel 21 and second surround 23 is the movement of air created solely by the movement of speaker cone 15 and first surround 19.
FIG. 1B is a top view of the prior art audio speaker/passive radiator shown in FIG. 1A with audio speaker 7 and passive radiator 21 in place.